Unless you outsource your holiday shopping, the start of winter means crowds of gift buyers, overworked-or worse, overeager-salespeople, and general retail pandemonium. But amid the chaos, there is one last bastion of quiescence and a touch of privacy: the dressing room.

For now.

Over the next several months, shoppers may discover they are not alone in there. Instead, they may be in the company of souped-up mirrors that can identify whatever button-down, trench coat, or polo shirt they are trying on. Enter the dressing room, and the looking glass will play a little tune and display promotional graphics for the designer of whatever you're trying on, product information (in a recent demonstration, the mirror recognized a "sea island cotton dress shirt" by British designer Nick Tentis), and even suggestions for coordinating items. Push a button (or the touch-sensitive glass) to request that a salesperson bring a different size or color.

The so-called "magic mirror" was developed by thebigspace, an experience-design company based in Milan, Italy, in collaboration with Infosys, an Indian tech company. The mirror is expected to appear in a select group of retailers' stores early next year.

Made of chemically treated glass, the mirror is unremarkable from the front, but this masks a sophisticated arsenal of technology, including a computer, an L.C.D. screen, a radio-frequency-identification reader, and an antenna. RFID transponders embedded in clothing tags bring the mirror to life.

While some shoppers may find it entertaining and perhaps helpful, the magic mirror was designed primarily to perform wonders for retailers. For starters, the retailers are competing with the increasingly interactive world of online shopping, where buyers have virtual personal assistants and group ratings at their disposal. According to Forrester Research, which is based in Cambridge, Massachusetts, online apparel sales will total $22.1 billion this year, up 21 percent from 2006, and brick-and-mortar retailers are feeling threatened.

With the high-tech mirrors, "retailers are buying the ability to provide an enhanced consumer experience," says Dick Lockard, C.E.O. of Thebigspace.

But the magic mirror may provide retailers far more powerful benefits. It may make it easier to hook shoppers on more expensive goods or push a designer's duds. It recognizes and remembers what clothes customers try on, creating what Devon Ferreira, a principal at Infosys, calls a "database of consumer intention." This information can be compared against the database of consumer action-the cash register-to analyze what's selling and what isn't. The data could affect not only the way retailers order and stock their merchandise but also how products are developed. For example, if customers find a certain pair of jeans appealing on the rack but not in the fitting room, designers will know to tweak them.

Infosys is also touting the mirror's ability to deter theft. In 2006, shoplifting accounted for $13.3 billion in retail losses, and companies lost 1.6 percent of sales to theft and fraud, according to a study released this June by the National Retail Federation and the University of Florida. Retailers have installed security tags, alarms, and video feeds to deter and catch thieves, but the mirror promises a more elegant solution. Say a customer in a store that has an average price point of $100 brings $5,000 of merchandise into a fitting room. The mirror would alert staff to a potential shoplifter-or to a big spender it would also be wise to pay special attention to.

The system is being marketed directly to retailers: Infosys has reached out to about 60 top companies among its existing customers, targeting mainly North American footwear and clothing manufacturers, and then markets in Europe and Asia. It is focusing on the lower high-end and higher middle-market retailers who want to expand customer service but not their payrolls. Infosys is cagey about who is biting but says that about four companies are currently on board. Priced with a subscription plan, the mirrors cost in the low-to-mid five figures per store annually.

One question: Where's the off button? There didn't appear to be one during the demonstration, but Ferreira says the mirror has one. "Consumer privacy is something we manage closely," he says.

It remains to be seen how receptive shoppers will be to getting down to their skivvies in front of such observant technology. Then again, maybe the images that dance across the screen will be lively enough to make customers forget to consider how they actually look.